[PATCH v5 00/20] Add gdb python scripts as kernel debugging helpers

[PATCH v5 00/20] Add gdb python scripts as kernel debugging helpers

[Jan Kiszka]

Version 5 comes with the following changes:
 - moved tutorial into Documentation/gdb-kernel-debugging.txt
 - improved caching of gdb.Type objects, ensure they are in sync with
   currently loaded symbols
 - added new functions and commands
    - lx_module -- Find module by name and return the module variable
    - lx_modvar -- Return global variable of a module
    - lx-lsmod -- List currently loaded modules

See http://lkml.indiana.edu/hypermail/linux/kernel/1210.0/01598.html for
the original description and

    git://git.kiszka.org/linux.git queues/gdb-scripts

for the latest version.

Jan

CC: "David S. Miller" <davem@davemloft.net>
CC: Fenghua Yu <fenghua.yu@intel.com>
CC: Kay Sievers <kay@vrfy.org>
CC: linux-doc@vger.kernel.org
CC: linux-ia64@vger.kernel.org
CC: linux-kbuild@vger.kernel.org
CC: Michal Marek <mmarek@suse.cz>
CC: Rob Landley <rob@landley.net>
CC: sparclinux@vger.kernel.org
CC: Tony Luck <tony.luck@intel.com>

Jan Kiszka (20):
  scripts/gdb: Add infrastructure
  scripts/gdb: Add cache for type objects
  scripts/gdb: Add container_of helper and convenience function
  scripts/gdb: Add module iteration helper
  scripts/gdb: Add lx-symbols command
  scripts/gdb: Add internal helper and convenience function to look up
    a module
  scripts/gdb: Add lx_modvar convenience function
  scripts/gdb: Add get_target_endianness helper
  scripts/gdb: Add read_u16/32/64 helpers
  scripts/gdb: Add lx-dmesg command
  scripts/gdb: Add task iteration helper
  scripts/gdb: Add helper and convenience function to look up tasks
  scripts/gdb: Add is_target_arch helper
  scripts/gdb: Add internal helper and convenience function to retrieve
    thread_info
  scripts/gdb: Add get_gdbserver_type helper
  scripts/gdb: Add internal helper and convenience function for per-cpu
    lookup
  scripts/gdb: Add lx_current convenience function
  scripts/gdb: Add helper to iterate over CPU masks
  scripts/gdb: Add lx-lsmod command
  scripts/gdb: Add basic documentation

 Documentation/gdb-kernel-debugging.txt |  155 +++++++++++++++++++++++++++++++
 Makefile                               |    5 +-
 scripts/Makefile                       |    3 +-
 scripts/gdb/Makefile                   |    9 ++
 scripts/gdb/dmesg.py                   |   63 +++++++++++++
 scripts/gdb/module.py                  |  149 ++++++++++++++++++++++++++++++
 scripts/gdb/percpu.py                  |  110 ++++++++++++++++++++++
 scripts/gdb/symbols.py                 |  147 +++++++++++++++++++++++++++++
 scripts/gdb/task.py                    |   99 ++++++++++++++++++++
 scripts/gdb/utils.py                   |  158 ++++++++++++++++++++++++++++++++
 scripts/gdb/vmlinux-gdb.py             |   29 ++++++
 11 files changed, 925 insertions(+), 2 deletions(-)
 create mode 100644 Documentation/gdb-kernel-debugging.txt
 create mode 100644 scripts/gdb/Makefile
 create mode 100644 scripts/gdb/dmesg.py
 create mode 100644 scripts/gdb/module.py
 create mode 100644 scripts/gdb/percpu.py
 create mode 100644 scripts/gdb/symbols.py
 create mode 100644 scripts/gdb/task.py
 create mode 100644 scripts/gdb/utils.py
 create mode 100644 scripts/gdb/vmlinux-gdb.py

-- 
1.7.3.4

[PATCH v5 01/20] scripts/gdb: Add infrastructure

[Jan Kiszka]

This provides the basic infrastructure to load kernel-specific python
helper scripts when debugging the kernel in gdb.

The loading mechanism is based on gdb loading for <objfile>-gdb.py when
opening <objfile>. Therefore, this places a corresponding link to the
main helper script into the output directory that contains vmlinux.

The main scripts will pull in submodules containing Linux specific gdb
commands and functions. To avoid polluting the source directory with
compiled python modules, we link to them from the object directory.

Due to gdb.parse_and_eval, we depend on gdb >= 7.1. We need to
pre-process the version string returned by gdb as some distros tend to
prefix it with their name.

This feature depends on CONFIG_DEBUG_INFO.

CC: Michal Marek <mmarek@suse.cz>
CC: linux-kbuild@vger.kernel.org
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---
 Makefile                   |    5 ++++-
 scripts/Makefile           |    3 ++-
 scripts/gdb/Makefile       |    9 +++++++++
 scripts/gdb/utils.py       |   17 +++++++++++++++++
 scripts/gdb/vmlinux-gdb.py |   22 ++++++++++++++++++++++
 5 files changed, 54 insertions(+), 2 deletions(-)
 create mode 100644 scripts/gdb/Makefile
 create mode 100644 scripts/gdb/utils.py
 create mode 100644 scripts/gdb/vmlinux-gdb.py

diff --git a/Makefile b/Makefile
index 2d3c92c..f0d2b2d 100644
--- a/Makefile
+++ b/Makefile
@@ -774,6 +774,9 @@ endif
 ifdef CONFIG_BUILD_DOCSRC
 	$(Q)$(MAKE) $(build)=Documentation
 endif
+ifdef CONFIG_DEBUG_INFO
+	$(Q)ln -fsn $(srctree)/scripts/gdb/vmlinux-gdb.py
+endif
 	+$(call if_changed,link-vmlinux)
 
 # The actual objects are generated when descending, 
@@ -1019,7 +1022,7 @@ MRPROPER_FILES += .config .config.old .version .old_version $(version_h) \
 		  Module.symvers tags TAGS cscope* GPATH GTAGS GRTAGS GSYMS \
 		  signing_key.priv signing_key.x509 x509.genkey		\
 		  extra_certificates signing_key.x509.keyid		\
-		  signing_key.x509.signer
+		  signing_key.x509.signer vmlinux-gdb.py
 
 # clean - Delete most, but leave enough to build external modules
 #
diff --git a/scripts/Makefile b/scripts/Makefile
index 01e7adb..3204b91 100644
--- a/scripts/Makefile
+++ b/scripts/Makefile
@@ -37,6 +37,7 @@ subdir-$(CONFIG_MODVERSIONS) += genksyms
 subdir-y                     += mod
 subdir-$(CONFIG_SECURITY_SELINUX) += selinux
 subdir-$(CONFIG_DTC)         += dtc
+subdir-$(CONFIG_DEBUG_INFO)  += gdb
 
 # Let clean descend into subdirs
-subdir-	+= basic kconfig package selinux
+subdir-	+= basic kconfig package selinux gdb
diff --git a/scripts/gdb/Makefile b/scripts/gdb/Makefile
new file mode 100644
index 0000000..34ccd06
--- /dev/null
+++ b/scripts/gdb/Makefile
@@ -0,0 +1,9 @@
+always := gdb-scripts
+
+$(obj)/gdb-scripts:
+ifneq ($(KBUILD_SRC),)
+	$(Q)ln -fsn $(srctree)/$(obj)/*.py $(objtree)/$(obj)
+endif
+	@:
+
+clean-files := *.pyc $(if $(KBUILD_SRC),*.py)
diff --git a/scripts/gdb/utils.py b/scripts/gdb/utils.py
new file mode 100644
index 0000000..f75eae6
--- /dev/null
+++ b/scripts/gdb/utils.py
@@ -0,0 +1,17 @@
+#
+# gdb helper commands and functions for Linux kernel debugging
+#
+#  common utilities
+#
+# Copyright (c) Siemens AG, 2011-2013
+#
+# Authors:
+#  Jan Kiszka <jan.kiszka@siemens.com>
+#
+# This work is licensed under the terms of the GNU GPL version 2.
+#
+
+import gdb
+import re
+
+gdb_version = re.sub("^[^0-9]*", "", gdb.VERSION)
diff --git a/scripts/gdb/vmlinux-gdb.py b/scripts/gdb/vmlinux-gdb.py
new file mode 100644
index 0000000..bcb45cc
--- /dev/null
+++ b/scripts/gdb/vmlinux-gdb.py
@@ -0,0 +1,22 @@
+#
+# gdb helper commands and functions for Linux kernel debugging
+#
+#  loader module
+#
+# Copyright (c) Siemens AG, 2012
+#
+# Authors:
+#  Jan Kiszka <jan.kiszka@siemens.com>
+#
+# This work is licensed under the terms of the GNU GPL version 2.
+#
+
+import os
+
+sys.path = [ os.path.dirname(__file__) + "/scripts/gdb" ] + sys.path
+
+from utils import gdb_version
+
+if gdb_version < "7.1":
+	print "NOTE: gdb 7.1 or later required for Linux helper scripts " \
+	      "to work."
-- 
1.7.3.4

Re: [PATCH v5 00/20] Add gdb python scripts as kernel debugging helpers

[Borislav Petkov]

On Tue, Jan 29, 2013 at 01:37:43PM +0100, Jan Kiszka wrote:
> Version 5 comes with the following changes:
>  - moved tutorial into Documentation/gdb-kernel-debugging.txt
>  - improved caching of gdb.Type objects, ensure they are in sync with
>    currently loaded symbols
>  - added new functions and commands
>     - lx_module -- Find module by name and return the module variable
>     - lx_modvar -- Return global variable of a module
>     - lx-lsmod -- List currently loaded modules
> 
> See http://lkml.indiana.edu/hypermail/linux/kernel/1210.0/01598.html for
> the original description and
> 
>     git://git.kiszka.org/linux.git queues/gdb-scripts
> 
> for the latest version.

Ok, I've seldomly shown any feelings when acking a patch{,set} besides
maybe "hm, ok, fine" but this patchset is very very cool and it is an
enormous fun playing with it.

So maybe this is the most enthusiasm I've shown sofar:

Emphatically-acked-by: Borislav Petkov <bp@suse.de>

Thanks Jan, very good work!

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
--

Re: [PATCH v5 01/20] scripts/gdb: Add infrastructure

[Tom Tromey]

>>>>> "Jan" == Jan Kiszka <jan.kiszka@siemens.com> writes:

Jan> +if gdb_version < "7.1":
Jan> +	print "NOTE: gdb 7.1 or later required for Linux helper scripts " \
Jan> +	      "to work."

FWIW you can just directly feature-test for the things you know you need.
Like:  if not hasattr(gdb, 'parse_and_eval'): ...
In this case, 7.1 is old enough that it probably doesn't matter.
For newer things, though, it is better to feature-test because distros
sometimes forward-port patches, so the version number isn't a reliable
indicator.

Tom